/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.table.planner.utils;

import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * Copied from {@link org.apache.flink.runtime.util.SingleElementIterator}.
 * Fix iterator to set available true.
 */
public final class SingleElementIterator<E> implements Iterator<E>, Iterable<E> {

	private E current;
	private boolean available = false;

	/**
	 * Resets the element. After this call, the iterator has one element available, which is the
	 * given element.
	 *
	 * @param current The element to make available to the iterator.
	 */
	public void set(E current) {
		this.current = current;
		this.available = true;
	}

	@Override
	public boolean hasNext() {
		return available;
	}

	@Override
	public E next() {
		if (available) {
			available = false;
			return current;
		} else {
			throw new NoSuchElementException();
		}
	}

	@Override
	public void remove() {
		throw new UnsupportedOperationException();
	}

	@Override
	public Iterator<E> iterator() {
		available = true;
		return this;
	}
}
